Flamingos Are Not Born Pink

Few animals are as firmly attached to a single colour as the flamingo. It is pink on lawn ornaments, pink on beach towels and pink in every child's drawing of a bird standing on one leg. It is tempting to assume that flamingos simply come that way, the way a zebra comes with stripes. They do not. A flamingo is born fluffy and pale, and the pink is something it has to eat its way into, one beakful at a time.

A newly hatched chick is covered in soft down that zoos describe as white or grey, and at first it is roughly the size of a tennis ball. According to San Diego Zoo, it even starts life with a straight pink bill and swollen pink legs, both of which turn black within a week. The adult colouring comes slowly. The Smithsonian's National Zoo notes that young flamingos take several years and several moults before they become properly pink.

The colour comes from food. Flamingos feed with their heads upside down in the water, sucking in water and mud and pumping it out through comb-like plates in their bills that trap algae and tiny creatures such as brine shrimp. Those foods are rich in carotenoids, the same family of pigments that makes carrots orange. The flamingo's body takes the pigments and deposits them in its growing feathers, legs and face. We eat carotenoids too, but nowhere near enough to turn orange.

Here is the strangest part. For the first days of its life a chick is fed a kind of milk, called crop milk, made in the upper digestive tract of its parents. Both mothers and fathers make it, and so can other adults acting as foster feeders. As the parents feed their chick, they are drained of their colour, and their plumage can fade to pale pink or almost white. The colour comes back once the chick is independent and the parents are eating for one again.

The pink is not even permanent in the feathers themselves. Once a flamingo feather has been shed, it quickly loses its colour. That is why zoos have to think carefully about food. San Diego Zoo feeds its flamingos a special pellet diet containing a pigment, and gives them water nearby so they can feed in their usual pumping style, keeping the flock, in the zoo's own words, in the pink.

How do we know the colour is dietary rather than built in? The clearest evidence comes from the birds themselves: chicks start out pale, adults lose colour while making crop milk, and flamingos that do not get enough carotenoids fade. Different species and populations also show different shades depending on what they eat, with American flamingos among the brightest, displaying red, pink or orange on their legs, bills and faces.

So the belief that flamingos are born pink is a myth, and a charming one to lose. The bird in the lawn ornament is really a record of a lifetime of meals. A flamingo that looks especially vivid is well fed, and one that looks a little faded may simply have been busy raising a very hungry chick.